1. Field of the Disclosure
The disclosure relates to a pressure control valve, with particular but not exclusive application to a pressure control valve which delivers a relatively constant pressure at the valve outlet when the pressure at the valve inlet reaches or exceeds the constant output pressure.
2. Related Technology
Pressure control valves are known, as are so-called constant pressure valves which purport to deliver a constant output pressure for varying input pressures. However some known constant pressure valves deliver a constant pressure only within a specified range of varying input pressures. Thus a constant pressure valve which may deliver a relatively constant output pressure of 300 KPA for varying input pressure within a range of from 300-500 KPA, may deliver an output pressure considerably in excess of 300 KPA if the input pressure were to increase to 1000 KPA.
One such valve is the subject of AU patent 602199 wherein outlet pressure is controlled by the biasing effect of a spring acting against a piston the face of which has applied to it the pressure at the valve outlet. The outlet pressure overcomes the force exerted by the spring to move the piston away from the outlet and into engagement with a valve seat proximate the valve inlet to close off a bore extending through the piston for providing fluid communication between the inlet and the outlet.